Many different types of data storage systems exist and are being used to store data cartridges at known locations and to retrieve those data cartridges from the storage locations so that data may be written to or read from those data cartridges. Such data storage systems are often referred to as “juke box” data storage systems, particularly if they can accommodate a large number of individual data cartridges.
A typical data storage system may include one or more different types of cartridge receiving devices for holding the various data cartridges. For example, one type of cartridge receiving device may comprise a cartridge storage rack or “magazine.” The cartridge storage racks or magazines usually include cartridge storage slots which serve as storage locations for the data cartridges. The various cartridge storage racks or magazines of the data storage system are commonly arranged so that they form one or more vertical and/or horizontal stacks, although other configurations are possible. Another type of cartridge receiving device may comprise a cartridge read/write device. The cartridge read/write device may be located adjacent a cartridge magazine, although the cartridge read/write device may be positioned at any convenient location.
The data storage system may also be provided with a cartridge handling system for transporting the data cartridges between the various cartridge receiving devices, e.g., between the cartridge storage racks and the cartridge read/write devices. A typical cartridge handling system may include a cartridge access device for accessing the various data cartridges contained in the cartridge receiving devices, as well as a positioning system for moving the cartridge access device among the various cartridge receiving devices contained in the data storage system.
Data storage systems of the type described above are usually connected to a host computer system (not shown) which may access or store data on the data cartridges. For example, if certain data contained on a particular data cartridge is desired, the host computer system will issue commands to a control system associated with the data storage system. In response to those commands, the control system will actuate the positioning system which moves the cartridge access device along the cartridge storage racks or magazines until the cartridge access device is positioned adjacent the desired data cartridge. The cartridge access device may then remove the desired cartridge from the cartridge storage rack and carry it to the cartridge read/write device. Once properly positioned adjacent the cartridge read/write device, the cartridge access device may insert the selected data cartridge into the cartridge read/write device so that the host computer may thereafter read data from or write data to the selected data cartridge. After the read/write operation is complete, the cartridge access device may remove the data cartridge from the cartridge read/write device and return it to its appropriate location in the cartridge storage rack.
It is often necessary or desirable for a system operator to periodically access one or more of the data cartridges contained within such a data storage system. For example, it may be necessary for the system operator to remove certain of the data cartridges from time to time if they become filled with data that is to be archived at another location. The system operator may then replace the filled data cartridges with blank or empty data cartridges. In another situation, the system operator may desire to remove one or more of the data cartridges and replace it or them with a substitute data cartridge or cartridges containing different data.
In order to accommodate the foregoing needs, many data storage systems are provided with an access panel to allow the system operator to access the data cartridges stored within the data system. Although such an arrangement does allow the system operator to access the data cartridges, it is usually difficult and cumbersome to implement in practice. For example, since the access panel needs to be removed in order to access the data cartridges, the data storage system must be temporarily shut-down or suspended in order to prevent injury to the system operator should the cartridge access device move while the system operator's hand is inside the data storage system. Another difficulty is that it is often difficult for the system operator to locate the particular data cartridges that are to be replaced. Still another disadvantage is that once the access panel has been replaced, it is necessary for the data storage system to re-inventory all the data cartridges contained therein. Such re-inventory processes are time consuming and difficult to justify, particularly if only one cartridge has been replaced. Nevertheless, the data storage system must re-inventory all of the data cartridges within the data storage system before it can be returned to service.
Partly in an effort to solve some of the aforementioned problems, data storage systems have been developed that include extendable drawers that can be opened to allow the system operator to access the data cartridges stored in the data storage systems. Such an extendable drawer is useful in that it allows the system operator to access one or more data cartridges without the need to remove a separate access panel.
Unfortunately, most drawer type of data cartridge exchange systems are not without their disadvantages. For example, if the system operator only wishes to access a data cartridge positioned near the front of the drawer, the system operator must nevertheless move all of the data cartridges within the drawer. In other words, by opening the drawer, the system operator renders all of the data cartridges within the drawer inaccessible to the cartridge handling system of the data storage system. Indeed, the data storage system will not be able to access any of the data cartridges within the drawer until the system operator finishes accessing the exposed data cartridges and closes the drawer.